Category: Apple Developper Connection

A lot of people these days appear to be under the impression that Macs have a BIOS, which is unfortunate because they actually have something much better – Macs have OpenFirmware. This is true for G4 Mac Minis, PowerBooks, iBooks, iMacs, eMacs, and Dual G5s… I could go on and on.
I got most of this info from experience and the Apple Developper Connection – if you’re not a member yet, sign up, it’s free.

You can get into OpenFirmware using this key sequence:

CMD-OPT-O-F

In detail, this means using two hands, holding “command”, “option” and “f” on the left and “o” with your right hand. Do this while booting your computer and you well hear two chimes. At the end of the chimes you will be greeted with an

On my G4 Mac Mini, for example, I can hold down the power button for roughly 10 seconds and I will hear the chimes – this should work for iMacs as well.

The OpenFirmware prompt that looks like this:

ok

0>

Congratulations, you’ve accessed your “BIOS” you switcher!

Now that we’ve passed this glorious milestone, we have some work to do. After all you came here for a reason right? (and not just to click on the ads, wink-wink nudge-nudge)

Some useful commands that save me time and time again, and enable reparation of the G4 Mac Mini:

Boot your Apple computer using the default boot device:

0 > mac-boot

Boot your Mac using the inserted CDROM at the yaboot directory for linux CDs:

0 > boot cd:,\install\yaboot

To eject a CDROM from your Mac:

0 > eject cd

If you have any other OpenFirmware tips to share, feel free to comment!